Actually the big issue about having microgravity on the moon is that the human skeleton loses calcium yearly because the compounds in our bones require gravity to be stable. So consequences of space exploration are a lot worse than allergies. A lot of the astronauts whohave come back have had accelerated osteoporosis.
To give you an idea of how bad this is they're estimating it's close to 1% of your bone mass disappearing per month that you're in space. If you stayed on the moon for just a single year you'd come back disabled with 88% of the bone density you left with.
Allegedly it won't be so bad on Mars because they are theorizing that it's a baseline amount of gravity which is required. And as a planet Mars has significantly more gravity than the moon. But this is just guess work. Personally I pity the very first baby born on these planets or the Moon.
